The present invention relates to reproduction machines of the type that employ bar lens arrays and in particular to an improved lens assembly and method for assembling the lens to facilitate mounting while ensuring the critical optical alignment necessary for the machine.
Reproduction machines commonly employ for their optics bar lens arrays such as those which are sold by the Nippon Sheet Glass Company of Japan under the trademark SELFOC. For reasons which are discussed in some detail in U.S. Pat. Nos. 4,059,345 and 4,147,412 it is critical that the lens array be precisely located with respect to the image and optic planes of the reproduction machine. As a result, it heretofore has been common to precisely locate the center of the bar lens and pass a mounting pin through the center as shown for example, in U.S. Pat. No. 4,653,894. The mounting pin engages mounting openings in the reproduction machine and thus insures the proper alignment of the lens array during subsequent mounting and disassembly of the lens as is required for routine maintenance.
Since the mounting pins in such prior art assemblies are pressed into holes in the SELFOC bar lens, the lens must be precisely machined thus resulting in a relatively expensive component. Any misalignment of either the mounting pins in the bar lens resulted in components that would not operate properly. Further, the tight fit between the bar lens and the mounting pins can cause stresses in the lens which could result in damage to or destruction of the lens. This is an especially serious concern since any oversizing of the mounting pins with respect to the bar lens opening could cause damage to the delicate bar lens and, unless the mounting pins are precisely located with respect to the bar lens opening there can be no assurance that the lens array will seat in its optically proper position within the reproduction machine. Bar lenses are also easily damaged by bending which causes delamination of the assembly and dislocation and fracture of individual glass elements. This problem is particularly serious where long bar lenses are used.